Toxins All around Us

Susan starts her day by jogging to the edge of town, cutting back through a cornfield for an herbal tea at the downtown Starbucks and heading home for a shower. It sounds like a healthy morning routine, but Susan is in fact exposing herself to a rogue’s gallery of chemicals: pesticides and herbicides on the corn, plasticizers in her tea cup, and the wide array of ingredients used to perfume her soap and enhance the performance of her shampoo and moisturizer. Most of these exposures are so low as to be considered trivial, but they are not trivial at all—especially considering that Susan is six weeks pregnant.

Scientists have become increasingly worried that even extremely low levels of some environmental contaminants may have significant damaging effects on our bodies—and that fetuses are particularly vulnerable to such assaults. Some of the chemicals that are all around us have the ability to interfere with our endocrine systems, which regulate the hormones that control our weight, our biorhythms and our reproduction. Synthetic hormones are used clinically to prevent pregnancy, control insulin levels in diabetics, compensate for a deficient thyroid gland and alleviate menopausal symptoms. You wouldn’t think of taking these drugs without a prescription, but we unwittingly do something similar every day.

An increasing number of clinicians and scientists are becoming convinced that these chemical exposures con­tribute to obesity, endometriosis, diabetes, autism, allergies, cancer and other diseases. Laboratory studies—mainly in mice but sometimes in human sub­jects—­have demonstrated that low levels of endocrine-disrupting chemicals in­duce subtle changes in the developing fetus that have profound health effects in adulthood and even on subsequent generations. The chemicals an expecting mother takes into her body during the course of a typical day may affect her children and her grandchildren.

This isn’t just a lab experiment: we have lived it. Many of us born in the 1950s, 1960s and 1970s were exposed in utero to diethylstilbestrol, or DES, a synthetic estrogen prescribed to pregnant women in a mistaken attempt to prevent miscarriage. An article in the June issue of the New England Journal of Medicine called the lessons learned about the effects of fetal human exposures to DES on adult disease “powerful.”

In the U.S., two federal agencies, the Food and Drug Administration and the Environmental Protection Agency, are responsible for banning dangerous chemicals and making sure that chemicals in our food and drugs have been thoroughly tested. Scientists and clinicians across diverse disciplines are concerned that the efforts of the EPA and the FDA are insufficient in the face of the complex cocktail of chemicals in our environment. Updating a proposal from last year, Senator Frank R. Lautenberg of New Jersey introduced legislation this year to create the Safe Chemicals Act of 2011. If enacted, chemical companies would be required to demonstrate the safety of their products before marketing them. This is perfectly logical, but it calls for a suitable screening-and-testing program for endocrine-disrupting chemicals. The need for such tests has been recognized for more than a decade, but no one has yet devised a sound testing protocol.

Regulators also cannot interpret the mounting evidence from laboratory studies, many of which use techniques and methods of analysis that weren’t even dreamed of when toxicology testing protocols were developed in the 1950s. It’s like providing a horse breeder with genetic sequence data for five stallions and asking him or her to pick the best horse. Interpreting the data would require a broad range of clinical and scientific experience.

That’s why professional societies representing more than 40,000 scientists wrote a letter to the FDA and EPA offering their expertise. The agencies should take them up on it. Academic scientists and clinicians need a place at the table with government and industry scientists. We owe it to mothers everywhere, who want to give their babies the best possible chance of growing into healthy adults.

ABOUT THE AUTHOR(S)

Patricia Hunt is professor of genetics in the School of Molecular Biosciences at Washington State University, Pullman.